First, I'm talking about a 2-zone system NOT a 2-stage system. I'm really tired of trying to explain the difference to the guys at Lowe's & Menards. They hear the number 2 and immediately shut down their brain.

Background:
I have a single-stage forced air Trane Furnace/AC. House is 2-story. First and 2nd floors have individual T'stats and separately zoned using a TrolAtemp relay system. The original (non-programmable) t'stats had an extra contact on the back-base connected to the heat-cool switch wired to blue & orange conductors. The balance of the t'stat wiring is a traditional 4-wire system (RGWY) The TrolAtemp system consists of two dampers in the supply ductwork that selects whether the supply air goes to that particular zone (1st or 2nd floor). If that floor (zone) doesn't need air, the damper on that supply duct closes and the air is only sent to the zone that needs it. Essentially, the furnace/AC doesn't know, or care, which t'stat in which zone is calling for heating/cooling. It simply runs when requested and the TempAtrol determines which stat is calling the system to run and opens the damper to that zone. Both dampers might be open if both t'stats are calling for the system or only one damper might be open if the t'stat in that zone is calling for the system to run. If neither t'stat is calling for the system to run, it doesn't matter bacause the fan isn't running anyway. Whew.. . Long explanation. If you've seen a TempAtrol system you will know all this aynway.

My question/problem
Most programmable T'stats I've found DO NOT have the additional contact necessary. Any suggestions for models that have the extra contact? I could make all this work with some 24 volt relays and some real McGiver engineering, but that's a bit Mickey Mouse. All I really need are programmable t'stats that have an extra contact on the heat/cool switch.

There are a number of digital thermostats that have the "O" and "B" terminels They make on cooling and heating respectfully. If you are looking at thermostats , look for the ones that say gas heating or heat pumps, these have the extra terminels "O" "B" These could be single stage as well. Honeywell , Total Line, White Rogers are but a few. Mike, I hope this helps

First, I'm talking about a 2-zone system NOT a 2-stage system. I'm really tired of trying to explain the difference to the guys at Lowes & Menards. They hear the number 2 and immediately shut down their brain.

Background:
I have a single-stage forced air Trane Furnace/AC. House is 2-story. First and 2nd floors have individual T'stats and separately zoned using a TrolAtemp relay system. The original (non-programmable) t'stats had an extra contact on the back-base connected to the heat-cool switch wired to blue & orange conductors. The balance of the t'stat wiring is a traditional 4-wire system (RGWY) The TrolAtemp system consists of two dampers in the supply ductwork that selects whether the supply air goes to that particular zone (1st or 2nd floor). If that floor (zone) doesn't need air, the damper on that supply duct closes and the air is only sent to the zone that needs it. Essentially, the furnace/AC doesn't know, or care, which t'stat in which zone is calling for heating/cooling. It simply runs when requested and the TempAtrol determines which stat is calling the the system to run and opens the damper to that zone. Both dampers might be open if both t'stats are calling for the system or only one damper might be open if the t'stat in that zone is calling for the system to run. If neither t'stat is calling for the system to run, it doesn't matter bacause the fan isn't running anyway. Whew . . . long explanation. If you've seen a TempAtrol system you will know all this aynway.

My question/problem
Most programmable T'stats I've found DO NOT have the additional contact necessary. Any suggestions for models that have the extra contact? I could make all this work with some 24 volt relays and some real McGiver engineering, but that's a bit Mickey Mouse. All I really need are programmable t'stats that have an extra contact on the heat/cool switch.
A late P.S. I found out that the original mfr of TrolAtemp (Trolex web URL Zonefirst | (http://www.zonefirst.com)) has a newer controller that uses standard 4-wire t'stats, but it would require I replace the entire TrolAtemp relay controller. I'm sure that's quite a few bucks.

Probably not necessary if you replace existing stats with the stats I mentioned , you would still have to buy stats with the new the new controller to upgrade to a digital stat. Many new digital stats are made for heat pumps and gas electric systems , more versatile.

Thanks for the quick response.. .
Internally, on the stats you mentioned, is blue (B) used in "heat" position and orange (O) used in the "cool" position? If so then they should work fine. I just want to make sure the functionality is correct before buying one of them. I'm not finding internal stat schematics on the mfr's web sites anymore, so I couldn't verify how they actually switch the orange & blue conductors. All they show is all the colors landed on the obvious terminals. That's great for the functionally impaired, but I want to make sure it does what I'm looking for before buying it. Since most of these stats are blister-packed, they are a pain to return once opened. You literally need to shred the package to open it.

That is correct , "O" makes when stat is in the cooling and "B' in the heating mode .

Thx Mucho for the quick reply.